Thanks for checking my gallery out...
No I never submitted anything to Marvel, much as I'd love to, I know I'm still not there yet. The closest I've come was a portfolio review with Josh Blaylock from Devil's Due... who said I need to keep practicing. As of a few months past, Marvel is no longer taking open submissions over the mail. Your best bet is to start making friends with pros who use this site, ask them if they can critique your work, and make some damn impressive stuff, and they might pass your name off to an editor, if you're very lucky. Also, digital Webbing's website has a classified section where you can try to find people looking for creative partners, and some of those projects become good portfolio pieces.
Other than that, read up on what editors are looking for, most publishers have a '
ortfolio guideline' somewhere on their site with things they look for, then once you think you have your best work possible together, head out to a con and plan to wait for hours in line for a chance to meet with an editor.
I did look at your gallery as well, and it looks like you have some real potential, the color job on that Scorpion piece was vibrant and sharp, and a lot of that Rhino piece was well designed. However, your penciling technique needs some honing, and some intensive anatomy work, but you're still a youngster, so you've got some time ahead of you to perfect your work before you start thinking about submitting to a major publisher. I suggest reworking a piece several times in pencil or blue-line pencil before starting your final design.
I wish you luck!